Great advances have been made in semiconductor technology in the last few years due largely to greater demands for more exotic circuits, denser circuit packing, larger memories, higher frequencies and greater speeds. These demands have resulted in circuits with elements of smaller size, smaller spacing between circuit elements, more precise location of circuit features, etc. The trend toward denser packing of circuit elements continues and is likely to continue for some time.
A particular case in point is in the fabrication of various semiconductor devices containing one or more compound semiconductors including indium phosphide and related compounds such as indium gallium arsenide phosphide and indium gallium arsenide. Typical devices are photodetectors, light-emitting diodes and semiconductor lasers.
A particularly important aspect of semiconducting processing is the introduction of the dopant to the semiconductor material. Traditional techniques involve gaseous diffusion from metal vapor (e.g., Zn, Cd, etc.) in sealed ampules. Sometimes other sources are used such as phosphides (e.g., ZnP.sub.2, CdP.sub.2 etc.) or arsenides (e.g., ZnAs.sub.2, CdAs.sub.2, etc.) in appropriate cases. For many applications, this procedure yields excellent results. Conventional doping techniques have been described in a number of references including a paper entitled, "Zn-Diffused In.sub.0.53 Ga.sub.0.47 As/InP Avalanche Photodetector" by Y. Matsushima et al, Applied Physics Letters, 35 (6) (Sept. 15, 1979) and "Low Dark Current, High Efficiency Planar In.sub.0.53 Ga.sub.0.47 As/InP P-I-N Photodiodes" by S. R. Forrest, IEEE Electron Device Letters, Vol. EDL-2, No. 11 (November 1981). Other references include "Planar Type Vapor-Phase Epitaxial In.sub.0.53 Ga.sub.0.47 As Photodiode" by N. Susa et al, IEEE Electron Device Letters, Vol. EDL-1, No. 4 (April 1980) and "Plasma Enhanced CVD Si.sub.3 N.sub.4 Film Applied to InP Avalanche Photodiodes", by N. Susa, Japanese Journal of Applied Physics, Vol. 19, page L675 (1980).